Technical Field
The present disclosure relates to a board inspection apparatus for inspecting both a surface and a rear face of a printed circuit board or the like.
Background Art
A printed circuit board with electronic components mounted on both a surface and a rear face thereof generally has electrode patterns formed on both a surface and a rear face of a base substrate that is formed from a glass epoxy resin, and resist films provided to protect these electrode patterns.
In a production line for mounting electronic components on such a printed circuit board, a procedure first prints solder paste at predetermined positions on both the surface and the rear face of the printed circuit board (solder printing process). The procedure subsequently applies an adhesive at the predetermined positions on both the surface and the rear face of the printed circuit board (adhesive applying process). The procedure subsequently mounts electronic components on both the surface and the rear face of the printed circuit board (mounting process). The electronic components are temporarily fastened by the viscosity of the solder paste or by means of the adhesive. The procedure then introduces the printed circuit board into a reflow furnace for soldering (reflow process).
For example, a board inspection apparatus configured to perform an inspection for the printing state of solder paste prior to mounting of components (solder printing inspection apparatus) or a board inspection apparatus configured to perform an inspection with regard to a printed circuit board after mounting of components (mounting inspection apparatus) may be provided in this production line.
An inspection apparatus configured to perform an inspection simultaneously with regard to both the surface and the rear face of the printed circuit board is known as this board inspection apparatus.
In the board inspection apparatus configured to perform an inspection simultaneously with regard to both the surface and the rear face, however, there is a possibility that part of light emitted toward one face side of the printed circuit board is transmitted through a hole pierced through the printed circuit board or through the glass epoxy resin of the base substrate and is leaked to the other face side of the printed circuit board. As a result, leakage of light from one face side is likely to affect and decrease the inspection accuracy with regard to inspection of the other face side of the printed circuit board.
A recently proposed inspection apparatus places illumination units at offset positions on the surface side and on the rear face side of the printed circuit board or performs an inspection simultaneously with regard to both the surface side and the rear face side of the printed circuit board that are irradiated with the light of the same color (as described in, for example, Patent Literature 1).